Requirement of Alfalfa Re-Sowing – Alfalfa Hay Farming
By: Muhammad Salman Naeem
Alfalfa crop is being cultivated this year on a large scale in Pakistan for green fodder as well as for hay & hay-lage purposes. Alfalfa is the major forage legume grown in approximately 45 million hectares worldwide. Rhodes grass hay has steadily been increasing cultivation share in Pakistan for a number of years now, considered a less demanding crop in hay as compared to Alfalfa hay. Forage is the foundation of all diets for ruminants..
In addition to supplying nutrition for many different types of livestock, forages contribute to healthy bio systems. There are many factors which decide when the time is right to rotate your Alfalfa fields, majorly local climate and growing conditions, but there are a few indicators that are consistent regardless of geography. Farmers consider Alfalfa a perennial crop and expect fixed profitable returns as they are getting from reasonable consistent yields in their Rhodes Grass crop.
Decreasing yield is the most obvious indicator that something is not right in your alfalfa field.
“Some farmers would record the weight of bales off of a field and they could tell that a stand is starting to decline, Some farmers would record the weight of chopped forage for silos off of fields, and if you follow a field over time and it starts to decline, then that’s the time to take it out. That’s the truest and final test.” Yield data can be helpful to farmers beyond simply recording yield. Yield data can also provide benchmarks for producers and possibly indicate how different fields might be improved and using this data in the coming years, choice of accurate seed germplasm is relatively a positive decision.
If the yield in your alfalfa field does not remain constant throughout the year, it could be one of a few reasons. Usually, yield is highly affected due to a pest attack, rainy season, fungal infestation, irrigation fluctuation, summer scalding and even time of irrigation. Irrigation during the day in hot summer days cause scald in crop. Steady decline over a number of years is to be expected with any crop, but experiencing drastic drops in your yield is another indicator. “Anytime your yield drops more than 10 percent, you really need to think about rotation,” says Glenn Shewmaker, extension forage specialist with the University of Idaho.
Type of Land
Optimum soil pH is above 6.3 and retention of moisture in fields plays a critical role in stand establishment. Hard soils (Clay soil, clay loamy soils) retain moisture for longer periods of time up to 150- 190 hours. Such soils are not suitable for commercial (hay making + hay-lage) alfalfa crop. Alfalfa grows in such soil as a seasonal fodder. Sandy and sandy loam soils are considered best for alfalfa crop. Moisture retention in this type of soil is not more than 72 hours and standing water seeps down in few hours after irrigation. Globally, Alfalfa crop is cultivated under central pivot system & rain gun systems. Advantage of these systems is, field is irrigated after short intervals but irrigation is made a few millimeters at one time. But in flood irrigation, a common method of irrigation in Pakistan, 3-inch water layer is applied in the field each time and it impact negatively in yield & growth.
Another sign of the alfalfa stand declining is the decrease in stand density. According to literature, one of the best ways to estimate yield is to count the number of stems per square foot.
The optimum number recommended by the University of Wisconsin – Madison is 55 stems per square foot. The easiest way to tell is counting the cut stems directly after harvesting. Generally suggested that counting 1 or 2 square feet in different parts of the field to help get an idea of what would be expected, than doing a visual assessment for the rest of the field. At sowing time, plants per square meter are above 90. Eventually plant population goes down in further cuts but stand development starts after the first cut. In the 2nd year, stand density per square foot is considered 25-30 but yield is not reduced due to the low number of stands. Yield per stand increases due to increasing number of shoots. Stand density in the Alfalfa field usually goes down due to wheel traffic of mowing, raking and the baling process. Generally 5 times a wheel moves in a field from cutting till cleaning the field. Wheel traffic in wet field’s shows severe effects in alfalfa field stands however effects in Rhodes grass & Rye grass fields are not so drastic.
Another indication of stand decline is an increase in weed pressure. “If we have a good, thick stand or we have an aggressively growing field, it will generally keep the weeds down,” Sowing at an appropriate time under a flood irrigation system may reduce weed pressure. Early sowing/ sowing above 30 0C are cause of severe weed pressure in field. Undersander states that for farmers harvesting their alfalfa, it is generally not worthwhile to put a herbicide on after the stand has become established because when an herbicide is applied to a weedy field, it may get rid of the weeds, but yield will not increase; it will merely be an additional cost of herbicide. Second weed pressure comes when weather starts to warm up. In the monsoon season under flood irrigation, it is quite difficult to control weeds in one or two cuts.
Uniformity of the field
Another sign of a waning stand is the uniformity (or lack thereof) in a field. Standing water in a field may cause root rot in a field and stand vigor will lose its compactness in the field. With flood irrigation, irrigated point for large areas also affect the uniformity of the field and cause root rot on a long term basis.
Pests and disease
Another sign your alfalfa stand needs to go is if you have high levels of pests or disease in your stand. “If you have a problem with rodents or any kind of issue that’s difficult to control, that’s going to affect your stand as well, Shewmaker says. As for insects or diseases that get into the soil, “Once it’s there and in the soil, the damage is just going to increase. That may be a time, if you do a good scouting job, to decide that it’s time.
“If you’ve been cutting every 28 days during the summer on a vegetative or pre-bud stage, each cutting, for four to six cuttings, you’re only going to get a couple years of good production out of that,”. “There are a lot of things that affect the health of the stand and the health of the individual plants in the stand.”
Taking individual conditions into consideration when contemplating crop rotation is always important, but paying attention to what your fields are telling you could save valuable time and money in the long run.
Source: Progressive FORAGE